Drilling apparatus

ABSTRACT

A drilling apparatus having a drill string with drill body attached extending into the bottom of a bore hole. The drill body carries a drill bit which is cutting into a drilling face. The lower portion of the bore hole is filled with drilling fluid which is recirculated therein. Compressed gas is supplied from the surface through the drill string to a manifold in the drill body to operate two eductor systems. The first system educts drilling fluid into a plurality of airstreams and then directs jets of this mixture against the drill bit and the drilling face, and the second system removes the mixture of gas, drilling fluid and cuttings from the drilling face. Cuttings are collected in a basket annularly disposed about the drill body.

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Meihhey Mar, M, W

[54] DRILLING AlPlP'AlltfitT Ufi 2,849,214 8/1958 Hall ...l75/324 [72]Inventor: John M McKinney Gainesville Va 2,880,965 4/1959 Bobo ..l75/69[73] Assignee: Mcliinney Drilling Compimy Primary Examiner-James A.Leppink I Film: m y 1970 Attorney Bll'Ch Swmd er McKle & Beckett [2|]Appl. No: 52,413 ABSTRACT A drilling apparatus having a drill stringwith drill body at- 521 U.S.Cll ..175/205, 175/69 thched extending thehotwm of a bore hole- The hill [51 1 lint. cl ..lE2l|b 21/88 bodycarries a hill hit which is cutting a dfilhhg face- The {58] Field oiSearch 175/205, 308, 208, 422, 69, the We is with drilling fluid which175 324; 166 105 1051 1053, 1054; 173 74 is recirculated therein.Compressed gas is supplied from the l l surface through the drill stringto a manifold in the drill body [56] References (med to operate twoeductor systems. The first system educts drilling fluid into a pluralityof airstreams and then directs jets UNITED STATES PATENTS of thismixture against the drill bit and the drilling face, and the secondsystem removes the mixture of gas, drilling fluid 2,660,250 1 1/1953Gage et al 175/308 and Cuttings f the drilling face Cuttings arecollected i 3 2,819,038 1/1958 Ecke] "175/308 basket annularly disposedabout the drill body. 2,035,350 3/1936 Stoll...... ..l75/308 1,525,2352/1925 Hansen 175/308 20 Unims, 4 Drawing Figures PATENTEUHAR 14 m2SHEET 1 BF 2 INVENTOR JOHN R. McKINNEY ATTORNEYS PAIENTEDMAR 14 I972 sum2 [1F 2 INVENTOR JOHN R. MCKINNEY f ATTORNEYS lDlltlllLlLllNG APPARATUSBACKGROUND OF THE INVENTION 1. Field This invention relates generally toapparatus for drilling bore holes and more particularly to a drillingapparatus in which the drill bit and drilling face are kept clean, andthe cuttings removed by mechanisms operated by compressed gas.

2. Prior Art The drilling of large bore holes for various purposes, andparticularly rock drilling of large diameter shafts, caissons and thelike, has become a highly developed art. As the drilling has become moredemanding, so has the need for apparatus which is capable of prolongedoperation in an efficient economical, and reliable manner. Generally,bore holes are drilled by means of a drill bit cutting into a drillingface at the bottom of the bore hole. The drill bit is attached to adrill string that extends to the surface. Among the problems encounteredin drilling are cooling the drill bit, removing the drill cuttings fromthe bore hole, and keeping the drill bit and drilling face clean. Inorder to alleviate such problems, a drilling fluid is usually introducedinto the hole in the form of a liquid having characteristics especiallysuited for the particular type of drilling. In many prior art devicesthis drilling fluid is continuously recirculated to and from thesurface, and is additionally utilized as a carrier to remove to thesurface the cuttings generated during drilling. In order to circulatethe drilling fluid through the bore hole with sufficient velocity tomove the suspended cuttings to the surface, the prior art systemsrequire pumps located on the surface. These pumps are expensive and arecharacterized by low reliability. The stream of circulating drillingfluid generated by such pumps frequently is not suffi ciently powerfulto continuously clean the drill bit and drilling face, to the extentnecessary for efficient operation so this problem remains.

in other of the prior art devices, drilling fluid is not pumped to thesurface, but is recirculated in the bottom of the bore hole. Cuttingsare removed from the bottom of the bore hole by this circulating fluidand are then captured in various ways for separate removal. Thesesystems utilize pumps installed within the bore hole for recirculatingthe drilling fluid, and such pumps suffer greatly from the environmentalconditions present in the bore hole and are unreliable over prolongedperiods of operation. In addition, these pumps tend to foul with thecuttings and contaminated drilling fluid. Again, the serious problem ofcontinuously cleaning the drilling face and the drill bit is not solvedby these devices, for they are not directed toward this end.

SUMMARY OF THE INVENTION This invention presents a new and novelapparatus for solv ing the problems present in the devices of the priorart. At the bottom of a drill string rotating in a bore hole is a drillbody which has a drill bit cutting into a drilling face. The drill bodyoperates in a supply of drilling fluid which is put into the bottom ofthe bore hole and which may be any conventional drilling fluid or mud. Acollection basket is carried by said drill body above said drill bit.The drill body has an interior discharge passageway extendinglongitudinally therein, which passageway has an inlet adjacent the drillbit in communica tion with the bottom of the bore hole and an outletspaced above the drill bit and directed into the collection basket.Conduit means is carried by the drill body outside of the dischargepassageway, which conduit means has inlet means communicating with thelower portion of the bore hole outside of the drill body and outletmeans communicating with the bottom of the bore hole adjacent the drillbit. Pump means is carried by the drill body to conduit drilling fluidfrom the bore hole downwardly through the conduit means into the bottomof the bore hole adjacent the drill bit and to conduct drilling fluidand cuttings from the bottom of the bore hole upwardly through thedischarge passageway to the collection basket which is constructed topermit the drilling fluid deposited therein to return to the bottom ofthe bore hole for recirculation.

Contained in the drill body are systems which clean the drill bit anddrilling face, agitate and suspend the drill cuttings and remove thecuttings from the area of the drilling face. A first system mixesdrilling fluid and compressed gas and then directs the mixture thusformed in a jet against the drill bit and the cutting face. This mixtureof high pressure gas and drilling fluid is extremely active and createsa. great deal of turbulence which cleans the drilling face and the drillbit, so that the drill bit constantly has new rock against which tooperate. The turbulence also insures that the cuttings are agitated andremain in suspension, so they can be easily removed from the area.

A second system continuously pulls the turbulent mixture of gas,drilling fluid and cuttings from the area of the drilling face. Themixture is propelled upwardly by the force of an eductor plus thecompressed gas bubbles present in the mixture to a series of separatortubes, where the gas is allowed to escape upward to the surface, whilethe cuttings settle into a collection basket. At periodic intervals, theentire drill string is removed from the hole and the basket is emptied.

It is an object of this invention to provide an improved drillingapparatus in which a turbulent jet mixture of compressed gas anddrilling fluid is used to continuously clean the drill bit and thecutting face.

Another object of this invention is to provide an improved drillingapparatus in which drill cuttings are continuously and positivelyremoved from the area of the drilling face.

Another object of this invention is to provide an improved drillingapparatus in which gas operated mechanisms are used to clean the drillbit and drilling face and to remove the cuttings therefrom.

Another object of this invention is to provide an improved drillingapparatus in which the drilling fluid is continuously recirculated inthe bottom of the bore hole.

Another object of this invention is to provide an improved drillingapparatus in which the drill cuttings are collected in a basket mountedon the drill body.

Another object of this invention is to provide an improved drillingapparatus which is efficient, economical and reliable over extendedperiods of time.

DESCRIPTION OF THE DRAWINGS FIG. l is an elevational showing of a drillbody in accordance with the instant invention. FIG. 2 is an elevation,partially in section, of the lower portion of the drill body of FIG. ll.

FIG. 3 is an elevation, partially in section, of the upper portion ofthe drill body of FIG. ll.

FIG. 4 is a bottom view of the drill body of FIG. 3.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to thedrawings, there is shown a bore hole it) having a drill face lll.Operating within bore hole 10 is a vertical drill body ll2. At thelowermost end of drill body I2 is a drill bit 13 with a plurality ofrolling cutters l4. Cutters Ml cut into drilling face 11 when drill body12 is rotated and generate from this a continuous stream of drillcuttings 15. Bore hole 10 is filled to a predetermined depth withdrilling fluid i6. Drill body 12 is attached to a hollow drill string17, which extends to the surface, by means of a gas supply tube 18,which is coaxial with drill body 12 and forms the structural backbone ofdrill body 12. Machinery on the surface at the top of the bore hole (notshown) rotates drill string 17 and thereby drill body 12 rotates also.Tube 13 conducts compressed gas from drill string 17 to an annularcompressed gas manifold 22 positioned immediately above drill bit 13 inthe lower portion of drill body 12. Communicating with compressed gasmanifold 22 by means of conduits 24 are a plurality of compressed gasoperated drilling fluid eductors 25, which protrude downwardly throughthe disc-shaped top 23 of drill bit 13. Each eductor 25 has a drillingfluid inlet 26 located above top 23 and a nozzle 27 beneath top 23 andadjacent to and directed toward cutters 14 and drilling face 11. Eductor25 can be any of the well known types such as a venturi type. Drillingfluid inlet 26 is separated from the area of drill bit 14 by top 23, sothat inlet 26 is educting relatively clean drilling fluid 16. However,inlet 26 is also equipped with a filter screen 28.

As shown in detail in FlGS. 2 and 3, compressed gas manifold 22 alsocommunicates by means of a plurality of gas passages 29 with anextraction eductor 30 which is centrally positioned at the base ofsupply tube 18 and is actually surrounded by manifold 22. Extractioneductor 30 has an inlet 31, communicating with the area in which drillbit 13 is operating,- of a discharge conduit 32 mounted internally ofand coaxially with outer tube 18. Eductor 30 pulls the mixture ofcompressed gas, drilling fluid, and cuttings from the area of drill bit13 and drilling face 11. Discharge conduit 32 terminates at its upperend in a distributor 33 having a plurality of distributor pipes 34 atright angles to the axis of conduit 32. A plurality of open endedvertically oriented cylindrical separator tubes 36 having top openings37 and bottom openings 38 receive the discharge from distributor pipes34 through openings 35 in the sides of tubes 36. Distributor tubes 34discharge into separator tubes 36 at 90 to the axis of tubes 36.

Disposed coaxially about tube 18 and spaced therefrom is a cuttingscollection basket 40. Basket 40 is removably mounted upon a basket base41 which has a sloping bottom 42. Affixed to passage 18 are a pluralityof radially oriented centering vanes 43 which engage the sides of basket40. The operation and the interaction of centering vanes 43 willhereinafter be explained. Basket 40 is positioned beneath separatortubes 36 to catch the drilling fluid 16 and cuttings l exiting throughbottom openings 38.

FIG. 2 shows a detail of a preferred arrangement of the various systemsset forth in the invention. To continuously clean cutters l4 anddrilling face 11, and to agitate and suspend cuttings 15, jets of highvelocity compressed gas and drilling fluid emanate from the plurality ofnozzles 27, in this case three, which are immediately adjacent to andaimed to sweep across cutters l4 and drilling face 11. As shown, one ofthe nozzles 27 is inclined about degrees in the direction of rotation ofthe drill bit 13. The other two nozzles 27 are shown inclined about 10toward the central axis of the drill bit. Other orientations andspecific inclinations may be employed. To produce each of the pressurejets from the nozzles 27, a portion of the compressed gas in manifold 22is bled through conduits 24 to operate eductors 25, each of which has aventuri section 45. The low pressure area created adjacent venturi 45causes drilling fluid 16 to be drawn in through inlet 26 and mixed withthe high velocity compressed motivating gas. Screen 28 is provided toinsure that debris is not drawn into this high velocity stream andimpacted against cutters 14. Nozzles 27 direct the high velocity jettoward cutters 14 and drilling face 11 at close range to insure thatparticles which adhere to the surface of cutters 14 are removed and thatdrilling face 111 is continuously swept clean of cuttings. In thismanner drilling face 11 constantly presents a clean surface on whichcutters 14 can operate effectively.

Continuing in reference to HO. 2, other streams of compressed gas aredirected from manifold 22 through a series of motivating fluid inlets 29which inject a plurality of compressed gas jets around the periphery ofevacuation eductor 30 to create a low pressure area in evacuationeductor 30 in the known manner. The inlets 29 are inclined inwardly atan angle of about and in addition are tapered slightly inwardly frombottom to top. In the device shown there are four inlets 29 spacedcircumferentially 90 degrees apart. Eductor draws through intake 31 theturbulent mixture of gas, drilling fluid 16 and cuttings 15 from thearea of drilling face l1, and delivers this mixture swiftly upwardthrough discharge conduit 32.

A study of the complete operation of a device constructed in accordancewith the instant invention will illustrate the advantages of theparticular interrelationship of elements. Drill string 17, havingattached thereto drill body 12 and drill bit 13, is lowered into thebottom of bore hole 10 and submerged in a predetermined amount ofdrilling fluid 16. As an example, with a drill body that is 16 feetlong, 8 to 10 feet of drilling fluid is effective, but other quantitiesof fluid can be used. When drill bit 13 contacts drilling face 11 anddrill string 17 is rotated, compressed gas is continuously supplied tomanifold 22 by means of the hollow drill string 17, through the tube 18.A portion of the compressed gas in manifold 22 is bled off to a seriesof eductors 25 which educt drilling fluid 16 into the compressed gasstream, creating a high velocity turbulent mixture which is directedtoward cutters 14 and drilling face 11 at close range by means ofnozzles 27. The jets of compressed gas and drilling fluid 16 are farmore effective to clean drill bits 14 and drilling face 11, and toagitate and suspend cuttings 15, than would be jets of drilling fluid 16alone, since they create a great deal more turbulence and bubblingcleansing action. Positioning nozzles 27 immediately adjacent the drillbit 14 and drilling face 11 renders the full force of the jetseffective.

The action of the jets of high pressure gas and drilling fluid 16 iscomplemented by the positive exhaust of the centrally mounted evacuationeductor 30, also operated by strams of compressed gas from manifold 22,which continuously evacuates the mixture of gas, drilling fluid l6 andcuttings 15 from the area of drilling face 11. The force of evacuationeductor 30, plus the turbulence created by the bubbles of gas entrainedin the mixture, keeps cuttings 15 in suspension and carries the mixtureswiftly through the discharge passageway which extends through dischargeconduit 32 to distributor 33, thence through openings 35 into separatortubes 36. The abrupt change in direction of flow and resultingturbulence in separator tubes 36 allows the gas to escape upward throughtop openings 37, while the drilling fluid 16 and cuttings 15 dropdownward through bottom openings 38 into collection basket 40. In thecourse of operation, basket 40 will fill to the top with drilling fluid16 which then continuously spills over to the bottom of the bore hole10, where his again inducted into the system through inlets 26.

At periodic intervals, the entire apparatus is removed from bore hole10, and at that time collection basket 40 can be emptied. Owing to thenovel construction of basket 40, which simply rests on its base 41,basket 40 need only be raised slightly from base 41 to allow thecuttings 15 which have been deposited therein to drop out the bottom byaction of inclined surface 42. Centering vanes 43 insure that the basketis properly aligned and reseated.

This invention provides a drilling apparatus in which a great deal ofturbulence is created in the area of drilling face 11 in order tocontinuously clean cutters 14 and drilling face 11. Complementing thisaction is a means for evacuating the cuttings from the area of drillingface 11. The combination of these two systems causes a positive, forcedcirculation of a turbulent mixture through the area of the drillingface, thus providing a more efiicient and reliable drilling apparatus.In the preferred embodiment described above the entire mechanism has nomoving parts, except for cutters 14, which may be of any known type. Thenovel means for separating the gas and cuttings 15 is simple andreliable, and has little chance of becoming clogged or otherwisemalfunctioning. Collection basket 40 is unique, for its requires aminimum of effort to empty and is self-cleaning, a great advantage inmachinery of this large size. Basket 40 can be equipped with holes orscreens (not shown) through which the drilling fluid 16 may drain awayfor recirculation, these holes or screens being of such size as tocontinuously remove smaller particles that might otherwise be carriedalong and recirculated with drilling fluid 16. Such cleaning screenscould obviously be provided at other points within the system. Othermeans for supplying the mixture of gas and drilling fluid to nozzles 25,such as mechanical pumps, could be used with this apparatus, as couldother means for evacuating mixture of gas, drilling fluid lb, andcuttings 115 from the area of drill face 111.

With this invention, the drilling fluid is permitted to rest relativelynon turbulently in the bore hole outside of the drill body. An annularskirt depending from the disc-shaped top 23 tends to confine theturbulent mixture of drilling fluid, gas and cuttings in the area of thedrill bits. Thus, this turbulent mixture is prevented from risingoutside of the drill body and is directed into the inlet 31 of theexhaust passageway. The cuttings are thus confined to the relativelysmall exhaust passageway from which collection of the cuttings may bemade more effectively than would be possible if the discharge mixture ofdrilling fluid, gas and cuttings were elevated from the drilling areathrough the relatively large space outside of the drill body. Moreover,substantially less power is required to discharge such mixture throughthe interior passageway rather than the space outside of the drill body.

it is to be understood that while preferred forms of the invention areherein illustrated and described, it is not to be limited to specificforms or arrangements of parts herein described and shown. The scope ofthe invention is to be determined by the claims.

lclaim:

1i. Apparatus for drilling a bore hole having a drilling face and asupply of drilling fluid therein comprising a drill string extendinginto said bore hole,

a drill body attached to drill string,

a drill bit carried by said drill body and having cutters operating insaid drilling fluid, said cutters engaging said drilling face andgenerating cuttings therefrom,

a plurality of nozzles in said drill body adjacent to said cutters andsaid drilling face and directed theretoward,

means for continuously supplying a mixture of compressed gas anddrilling fluid through said nozzles to clean said cutters and saiddrilling face and to agitate and suspend said cuttings, said meansincluding a plurality of compressed gas operated drilling fluid eductorsin communication with said bore hole and educting drilling fluidtherefrom, and

evacuating means for removing said mixture of gas, drilling fluid andcuttings from adjacent said drilling face.

2. The apparatus of claim ll wherein said means for supply ing a mixtureof compressed gas and drilling fluid and said evacuating means aremotivated by compressed gas.

3. The apparatus of claim 2 further comprising means carried by saiddrill string adjacent said drill body for separating said cuttings fromsaid mixture of gas, drilling fluid and cuttings, and means carried bysaid drill string adjacent said drill body for collecting said cuttings.

d. The apparatus of claim 3 wherein said means for collecting saidcuttings comprises a collection basket carried by said drill body and incommunication with said means for separating said cuttings, saidcollection basket including a base portion having a downwardly andoutwardly sloping bottom and a generally cylindrical side portionsupported by said base portion and axially separable therefrom, wherebysaid cuttings will be ejected from said collection basket by action ofsaid sloping bottom when said side portion is separated axially fromsaid base portion.

5. Apparatus for drilling a bore hole having a drilling face and asupply ofdrilling fluid therein comprising a drill string extending intosaid bore hole,

a drill body attached to said drill string,

a drill bit carried by said drill body and having cutters operating insaid drilling fluid, said cutters engaging said drilling face andgenerating cuttings therefrom,

a plurality of nozzles in said drill body adjacent to said cutters andsaid drilling face and directed theretoward,

means for continuously supplying a mixture of compressed gas anddrilling fluid through said nozzles to clean said cutters and saiddrilling face and to agitate and suspend said cuttings, said meanscomprising a compressed gas supply passage carried by said drill string,a compressed gas manifold in said drill body communicating with said gassupply passage by means of a gas supplytube, and a plurality ofcompressed gas operated drilling fluid eductors, each of said eductorshaving a gas inlet in communication with said compressed gas manifold,an eduction inlet in communication with said bore hole to educt drillingfluid, and an outlet communicating with said nozzle, and

evacuating means for removing said mixture of gas, drilling fluid andcuttings from adjacent said drilling face.

6. The apparatus of claim 5 wherein said drill bit further comprises adisc-shaped top covering said cutters, and wherein said drilling fluideductors protrude through said top, said eduction inlets being abovesaid top and said outlet communicating with said nozzles below said top.

7. The apparatus of claim 5 wherein said evacuating means comprises acompressed gas operated evacuation eductor having a gas inlet incommunication with said compressed gas manifold, an eduction inletadjacent to said drill bit, and a discharge conduit, whereby the mixtureof gas, drilling fluid, and cuttings is educted from the area adjacentsaid drill bit and passed into said discharge conduit.

8. The apparatus of claim 7 further comprising means carried by saiddrill string adjacent said drill body for separating said cuttings fromsaid mixture of gas, drilling fluid and cuttings, and

means carried by said drill string adjacent said drill body forcollecting said cuttings.

9. The apparatus of claim 8 wherein said means separating said cuttingscomprises a distributor communicating with said eductor dischargeconduit,

a plurality of generally vertically oriented cylindrical separator tubeshaving open tops and open bottoms communicating with said distributorthrough openings in the wall of said separator tubes, said separatortubes being oriented perpendicular to the direction of discharge of saiddistributor, whereby the turbulence in said separator tubes allows saidgas to escape upward through said open tops while said cuttings and saiddrilling fluid exit downward through said open bottoms,

and wherein said collecting means comprises a collection basketpositioned beneath said open bottoms of said separator tubes.

W. The apparatus of claim 9 wherein said evacuation eductor and saiddischarge tube are centrally located in and coaxial with said drillbody, wherein said compressed gas manifold is circumferentially disposedabout said evacuation eductor, and wherein said gas supply tube iscoaxia'lly disposed about said evacuation eductor discharge tube.

ill. The combination of claim wherein said distributor is perpendicularto the axis of said evacuator discharge tube, and wherein saidcollection basket is disposed about and coaxial with said drill body.

112. The apparatus of claim ll wherein said collection basltet comprisesa base portion attached to said drill body and having a bottom slopingdownwardly and outwardly from the center thereof,

a generally cylindrical side portion supported by said base portion andaxially separable therefrom, and

a plurality of collection basket centering vanes attached to said drillbody and extending radially outwardly therefrom to contact said sideportion.

l3. An apparatus for drilling a bore hole and recirculating a drillingfluid contained in the lower portion of the bore hole which comprises:

a drill body adapted for suspension from a drill string,

a drill bit carried by said drill body at the bottom thereof and havingcutting means operable in the drilling fluid,

a collection basket carried by said drill body above said drill bit,

said drill body having an interior discharge passageway extendinglongitudinally therein, said passageway having an inlet adjacent saiddrill bit in communication with the bottom of the bore hole and anoutlet spaced above said drill bit and directed into said collectionbasket,

conduit means carried by said drill body outside of said passageway,said conduit means having inlet means communicating with the lowerportion of the bore hole outside of said drill body and outlet meanscommunicating with the bottom of the bore hole adjacent said drill bit,

pump means carried by said drill body to conduct drilling fluid from thebore hole downwardly through said conduit means into the bottom of thebore hole adjacent said drill bit and to conduct drilling fluid andcuttings from the bottom of the bore hole upwardly through saiddischarge passageway to said collection-basket, said basket beingconstructed to permit the drilling fluid deposited therein to return tothe bottom of the bore hole for recirculation.

14. The apparatus of claim 13 wherein said conduit means comprises aplurality of conduits spaced circumferentially around said drill bodyand said outlet means comprises a plurality of nozzles. I

15. The apparatus of claim 14 wherein said pump means includes aplurality of gas operated eductors in said conduits.

16. The apparatus of claim 15 wherein said pump means further includes agas operated eductor in said passageway.

17. The apparatus of claim 13 wherein said pump means comprises aplurality of pumps in said conduit means and said passageway.

18. The'apparatus of claim 17 wherein each of said pump means comprisesa gas operated eductor.

19. The apparatus of claim 13 wherein said pump means comprises gasoperated eductor means.

20. The apparatus of claim 19 wherein said passageway outlet comprisesmeans to separate the gas from the drilling fluid and cuttings.

1. Apparatus for drilling a bore hole having a drilling face and asupply of drilling fluid therein comprising a drill string extendinginto said bore hole, a drill body attached to drill string, a drill bitcarried by said drill body and having cutters operating in said drillingfluid, said cutters engaging said drilling face and generating cuttingstherefrom, a plurality of nozzles in said drill body adjacent to saidcutters and said drilling face and directed theretoward, means forcontinuously supplying a mixture of coMpressed gas and drilling fluidthrough said nozzles to clean said cutters and said drilling face and toagitate and suspend said cuttings, said means including a plurality ofcompressed gas operated drilling fluid eductors in communication withsaid bore hole and educting drilling fluid therefrom, and evacuatingmeans for removing said mixture of gas, drilling fluid and cuttings fromadjacent said drilling face.
 2. The apparatus of claim 1 wherein saidmeans for supplying a mixture of compressed gas and drilling fluid andsaid evacuating means are motivated by compressed gas.
 3. The apparatusof claim 2 further comprising means carried by said drill stringadjacent said drill body for separating said cuttings from said mixtureof gas, drilling fluid and cuttings, and means carried by said drillstring adjacent said drill body for collecting said cuttings.
 4. Theapparatus of claim 3 wherein said means for collecting said cuttingscomprises a collection basket carried by said drill body and incommunication with said means for separating said cuttings, saidcollection basket including a base portion having a downwardly andoutwardly sloping bottom and a generally cylindrical side portionsupported by said base portion and axially separable therefrom, wherebysaid cuttings will be ejected from said collection basket by action ofsaid sloping bottom when said side portion is separated axially fromsaid base portion.
 5. Apparatus for drilling a bore hole having adrilling face and a supply of drilling fluid therein comprising a drillstring extending into said bore hole, a drill body attached to saiddrill string, a drill bit carried by said drill body and having cuttersoperating in said drilling fluid, said cutters engaging said drillingface and generating cuttings therefrom, a plurality of nozzles in saiddrill body adjacent to said cutters and said drilling face and directedtheretoward, means for continuously supplying a mixture of compressedgas and drilling fluid through said nozzles to clean said cutters andsaid drilling face and to agitate and suspend said cuttings, said meanscomprising a compressed gas supply passage carried by said drill string,a compressed gas manifold in said drill body communicating with said gassupply passage by means of a gas supply tube, and a plurality ofcompressed gas operated drilling fluid eductors, each of said eductorshaving a gas inlet in communication with said compressed gas manifold,an eduction inlet in communication with said bore hole to educt drillingfluid, and an outlet communicating with said nozzle, and evacuatingmeans for removing said mixture of gas, drilling fluid and cuttings fromadjacent said drilling face.
 6. The apparatus of claim 5 wherein saiddrill bit further comprises a disc-shaped top covering said cutters, andwherein said drilling fluid eductors protrude through said top, saideduction inlets being above said top and said outlet communicating withsaid nozzles below said top.
 7. The apparatus of claim 5 wherein saidevacuating means comprises a compressed gas operated evacuation eductorhaving a gas inlet in communication with said compressed gas manifold,an eduction inlet adjacent to said drill bit, and a discharge conduit,whereby the mixture of gas, drilling fluid, and cuttings is educted fromthe area adjacent said drill bit and passed into said discharge conduit.8. The apparatus of claim 7 further comprising means carried by saiddrill string adjacent said drill body for separating said cuttings fromsaid mixture of gas, drilling fluid and cuttings, and means carried bysaid drill string adjacent said drill body for collecting said cuttings.9. The apparatus of claim 8 wherein said means separating said cuttingscomprises a distributor communicating with said eductor dischargeconduit, a plurality of generally vertically oriented cylindricalseparator tubes having open tops and open bottoms communicating withsaid distriButor through openings in the wall of said separator tubes,said separator tubes being oriented perpendicular to the direction ofdischarge of said distributor, whereby the turbulence in said separatortubes allows said gas to escape upward through said open tops while saidcuttings and said drilling fluid exit downward through said openbottoms, and wherein said collecting means comprises a collection basketpositioned beneath said open bottoms of said separator tubes.
 10. Theapparatus of claim 9 wherein said evacuation eductor and said dischargetube are centrally located in and coaxial with said drill body, whereinsaid compressed gas manifold is circumferentially disposed about saidevacuation eductor, and wherein said gas supply tube is coaxiallydisposed about said evacuation eductor discharge tube.
 11. Thecombination of claim 10 wherein said distributor is perpendicular to theaxis of said evacuator discharge tube, and wherein said collectionbasket is disposed about and coaxial with said drill body.
 12. Theapparatus of claim 11 wherein said collection basket comprises a baseportion attached to said drill body and having a bottom slopingdownwardly and outwardly from the center thereof, a generallycylindrical side portion supported by said base portion and axiallyseparable therefrom, and a plurality of collection basket centeringvanes attached to said drill body and extending radially outwardlytherefrom to contact said side portion.
 13. An apparatus for drilling abore hole and recirculating a drilling fluid contained in the lowerportion of the bore hole which comprises: a drill body adapted forsuspension from a drill string, a drill bit carried by said drill bodyat the bottom thereof and having cutting means operable in the drillingfluid, a collection basket carried by said drill body above said drillbit, said drill body having an interior discharge passageway extendinglongitudinally therein, said passageway having an inlet adjacent saiddrill bit in communication with the bottom of the bore hole and anoutlet spaced above said drill bit and directed into said collectionbasket, conduit means carried by said drill body outside of saidpassageway, said conduit means having inlet means communicating with thelower portion of the bore hole outside of said drill body and outletmeans communicating with the bottom of the bore hole adjacent said drillbit, pump means carried by said drill body to conduct drilling fluidfrom the bore hole downwardly through said conduit means into the bottomof the bore hole adjacent said drill bit and to conduct drilling fluidand cuttings from the bottom of the bore hole upwardly through saiddischarge passageway to said collection basket, said basket beingconstructed to permit the drilling fluid deposited therein to return tothe bottom of the bore hole for recirculation.
 14. The apparatus ofclaim 13 wherein said conduit means comprises a plurality of conduitsspaced circumferentially around said drill body and said outlet meanscomprises a plurality of nozzles.
 15. The apparatus of claim 14 whereinsaid pump means includes a plurality of gas operated eductors in saidconduits.
 16. The apparatus of claim 15 wherein said pump means furtherincludes a gas operated eductor in said passageway.
 17. The apparatus ofclaim 13 wherein said pump means comprises a plurality of pumps in saidconduit means and said passageway.
 18. The apparatus of claim 17 whereineach of said pump means comprises a gas operated eductor.
 19. Theapparatus of claim 13 wherein said pump means comprises gas operatedeductor means.
 20. The apparatus of claim 19 wherein said passagewayoutlet comprises means to separate the gas from the drilling fluid andcuttings.